Extension sideloaded via appx not working and no Turn it on button

Fixed Issue #12568910


Ruud v.
Jun 29, 2017
This issue is public.
Found in
  • Microsoft Edge
Found in build #
Reported by 1 person

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Steps to reproduce

We’ve created a pretty basic extension which should change alter the user-agent http header for http requests to certain (internal) domains. The extension is very similar to the example from https://github.com/mdn/webextensions-examples/tree/master/user-agent-rewriter

This extension works in development environment but it seems very difficult to enable it in normal user environment.

The extension is packed to a appx application
The application is digitaly signed using a code signing certificate
The signed application is imported into an application in SCCM (2012R2)

Client workstation (Windows 10 build 1704) has code signing certificate as trusted publisher.
Installation of LOB is allowed by Settings (Sideload apps enabled).
The client workstation is domain joined.

The SCCM application is target to a device collection with required installation. This all seems to work fine.

After installation the extension is visible in Edge: (menu -> Extensions). The extension is turned on(!) without user intervention. Well, it says it’s turned on but it does NOT do what it should do. This is tested by using the F12 developer tools to see the user-agent header sent with the proper http requests.

There is NO ‘Turn it on’/’Keep it off’ dialog present. I would expect this dialog to be present after reading https://docs.microsoft.com/en-us/microsoft-edge/extensions/extensions-for-enterprise ‘Behavior of sideloaded extensions’)

After many attempts I found a way to get the extension working:

  • about:flags -> Enable extension developer features (this might put your device at risk)
  • restart Edge
  • extensions -> click my extension -> Inspect: Background page (which opens a developer tools window for this extension).

Now the extension is working. And it will keep working even after disabling the developer features (though after uninstall/install off the extension/appx it starts over again). So it seems this ‘developer action’ triggers edge to really enable this extension.

I would expect a way to install the extensions with SCCM (unattended) and then it should either be (preferably) enabled (and working immediately) or giving the user a dialog to enable it. It makes no sense to require end users to enable developer features and actually having them to open the background page to get an extension to work.

Thanks in advance for checking.


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    Comments and activity

    • Microsoft Edge Team

      Changed Assigned To to “James M.”

    • Hello,

      Thank you for providing this information about the issue. A non-persistent background script will not load until it is needed. Perhaps you should set "persistent": true in your manifest.

      Best Wishes,
      The MS Edge Team

    • Microsoft Edge Team

      Changed Status to “Confirmed”

    • Thank you for checking and confirming.

      Regarding the suggestion to set the ‘persistent’ property to true; would it be useful to try or is it already clear this will not fix it?

      Kind regards,

    • Hello,

      You should make your background script persistent to see if that helps.

      Best Wishes,
      The MS Edge Team

    • Ok, changed “persistent” property to true:

        "background": {
          "scripts": ["useragent.js"],
          "persistent": true

      Bumped version etc. and deployed this new version to a test PC. It does not change the behavior regarding this issue.

      Further, I tested on Windows 10 build 1607/Edge 38.14393.1066.0. There behavior is like expected and described in https://docs.microsoft.com/en-us/microsoft-edge/extensions/extensions-for-enterprise

      Of course would like to have it working on latest Edge too.

    • Microsoft Edge Team

      Changed Status from “Confirmed” to “Fixed”

    • Hello,

      Thank you for providing this information about the issue. We have confirmed the problem, and we are working on a solution for a future build of Edge. We are presently tracking this issue as a duplicate of an existing internal bug report. We look forward to additional feedback you may have on how we can improve Microsoft Edge.

      Best Wishes,
      The MS Edge Team

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